Vienna, Mar 12 (IANS): A knife-wielding 26-year-old Austrian was shot dead outside the Iranian ambassador's residence here after he attacked a guard, police said.
The assailant ambushed the lone guard on sentry duty late night and injured him on the arm, reports Xinhua news agency.
The attacked died on the spot after the guard opened fire, the police added.
The motive behind the attack remains unknown.